Interseeding annual warm‐season grasses into temperate pasturelands: Forage accumulation and composition

Abstract

Interseeding annual warm‐season grasses into pastureland dominated by perennial cool‐season grasses may be a strategy to reduce shortage of forage. Field trials were conducted at three Nebraska (Mead, North Platte, and Sidney) and two Kansas (Hays and Mound Valley) locations in 2015–2016 (10 environments) to evaluate forage production responses to six interseeded annual warm‐season grass—corn (Zea mays L.), forage sorghum (Sorghum bicolor [L.] Moench), pearl millet (Pennisetum glaucum [L.] R. Br.), sudangrass (S. bicolor [L.] Moench ssp. drummondii [Nees ex Steud.] de Wet & Harlan), a sorghum–sudangrass hybrid (S. bicolor × S. bicolor var. sudanense), and an unseeded control—and two harvest frequency (once at 90 d and twice at 45 and 90 d after interseeding) treatments. Across environments, total forage accumulation was 146–214% and 100–102% greater in sudangrass and sorghum–sudangrass interseeded than unseeded pastures when harvested once and twice after interseeding, respectively. In smooth bromegrass (Bromus inermis Leyss.) pastures, interseeding sudangrass and sorghum–sudangrass increased forage accumulation in both years at Mead but in only one year at North Platte. In tall fescue (Lolium arundinaceum [Schreb.] Darbysh.) pastures, interseeding forage sorghum and sorghum–sudangrass increased forage accumulation by 103–211% relative to unseeded pastures. Interseeding annual warm‐season grasses presents an effective strategy to increase forage accumulation in humid pasturelands harvested once or twice after interseeding (Mead and Mound Valley). In semiarid pasturelands, forage responses to interseeding will vary from year‐to‐year depending on timing and amount of precipitation, but forage accumulation can be significant.

Interseeding annual warm‐season grasses into pastures: Forage nutritive value and yields

“…Warm-season grass interseeding occurred post-flowering and harvest of existing cool-season grasses in spring. Our companion paper provided specific seeding methods, row spacings, seeding depths, interseeding dates, and harvesting dates (Guretzky et al, 2020). Upon warm-season grass emergence, each subplot received granular urea at 67 kg N ha −1 .…”

“…Estimate statements were used to compute best linear unbiased predictions (BLUP) of means and mean differences among interseeded species within environments in the 45-d harvest and among harvest frequencies and interseeded species within environments in the 90-d harvest according to methodology described by Gbur et al (2012). We then computed and provided LSD values using the SE associated with each mean difference BLUP (i.e., to avoid listing F and P values of each specific BLUP) as we did in the companion study (Guretzky et al, 2020).…”

“…An option that has received limited evaluation is interseeding annual warm‐season grasses within existing perennial cool‐season grass pastures. Recently, we found that interseeding sudangrass and sorghum–sudangrass within improved perennial cool‐season grass pastures increased forage accumulation by 100–214% compared to unseeded pastures across eight environments in Kansas and Nebraska (Guretzky et al., 2020). Environments varied in responses, however.…”

“…An option that has received limited evaluation is interseeding annual warm-season grasses within existing perennial cool-season grass pastures. Recently, we found that interseeding sudangrass and sorghum-sudangrass within improved perennial cool-season grass pastures increased forage accumulation by 100-214% compared to unseeded pastures across eight environments in Kansas and Nebraska (Guretzky et (Guretzky et al, 2020). In this research, we presented a companion study that evaluated how harvest frequencies and interseeding annual warm-season grasses affected crude protein (CP), neutral detergent fiber (NDF), and in vitro organic matter digestibility (IVOMD) concentrations and yields.…”

“…In a semiarid environment with crested wheatgrass, no forage accumulation benefits were observed with interseeding either year. Across environments, harvesting pastures twice at 45 and 90 d after interseeding reduced forage accumulation compared to harvesting once at 90 d after interseeding, but questions remained about effects on nutritive value (Guretzky et al., 2020). In this research, we presented a companion study that evaluated how harvest frequencies and interseeding annual warm‐season grasses affected crude protein (CP), neutral detergent fiber (NDF), and in vitro organic matter digestibility (IVOMD) concentrations and yields.…”